1. Field of the Invention
This invention relates to communications and statistical analysis of vehicle movement. More particularly, the invention relates to communication with vehicles for the purpose of supplying traffic condition information and analyzing data relating to traffic conditions.
2. Description of Related Art
Conventional on-vehicle guidance systems are usually stand-alone applications wherein the traffic data are static and cannot be easily dynamically updated. Consequently, the proposed routes are accurate only under ideal traffic conditions. The stand-alone versions cannot take into account current traffic jam conditions or real time emergencies. Hence, even when a so-called xe2x80x9coptimal routexe2x80x9d is found, it may not be usable solution in real time situations and can only be used as a general recommendation. Other systems rely on electronic and optical sensors situated at various key locations to measure and update the current traffic loads. These systems are typically costly to install and to maintain and to be effective they must be distributed over large sectors of roads. Still other real time traffic control systems utilize real time field information typically gathered from various service vehicles such as traffic police, ambulances, road maintenance teams, etc., which is usually transmitted by radio to the control center and from there broadcasted to the public.
Use of a database for determining traffic jams and other bottleneck situations is addressed in U.S. Pat. No. 5,699,056. Data is obtained from traveling vehicles, including their IDs, positions, times, and speeds. A jam is presumed if an average speed of a block of vehicles is less than a predetermined value. This arrangement requires that data concerning relevant conditions of a large number of road sections be provided. The prior art requires evaluation of vehicle speeds and averaging them over a block. This seemingly innocuous operation may highly problematic, however, within a traffic jam as many if not all speed measurements may return zero values. In other words, speed as a function of time may be wildly discontinuous and measuring it on time grid of a minute may prove highly inaccurate. The definition of blocks is not quite clear. No technique is given for partitioning the vehicles into blocks. The number of roads or more precisely, sections of roads may be very large, say, tens of thousands. It may be difficult to cover them all, i.e. store all the relevant data, process and update it on-line. An important point in his solution is evaluating vehicle speeds and averaging them over a block. This seemingly innocuous operation may highly problematic; however, within a traffic jam as many if not all speed measurements may return zero values. In other words, speed as a function of time may be wildly discontinuous and measuring it on time grid of a minute may prove highly inaccurate.
Koutsopoulos and Xu""s paper is theoretical, and uses mathematical techniques and computer simulations for studying various methods of predicting future travel times under conditions of traffic congestion. Their results are interesting but they cover a tiny simulation model under a number of assumptions which may or may not be valid in large scale systems.
A comprehensive and obviously expensive experimental project ADVANCE is described in a series of technical reports obtainable at the Web site http://jungle.dis.anl.gov/advance. Many of their algorithmic decisions appear to be similar though not identical to ours while some of the most significant differences may be summarized as follows. They used xe2x80x9cpurexe2x80x9d GPS technology coupled with RF transmitters for transmitting location information from the equipped vehicles to the base station. Their fleet of equipped vehicles was extremely small (about 80 cars) and experimental. As opposed to this, we propose to utilize the GSM/GPS technology available from a number of telecommunications operators and quickly becoming an industry standard. As a result, our fleet of vehicles is going to be limitless for all practical purposes. Furthermore, in ADVANCE all route planning was performed in vehicles which necessitated maintenance of updated databases in all vehicles. In our system, all planning is done at the central server which greatly facilitates system""s functioning and makes vehicles""s equipment simpler and less costly.
Other proposed methods and systems for determination of dynamic traffic information and traffic events use wide coverage mobile telephone network such as GSM or CDMA. For example, U.S. Pat. No. 6,012,012 utilizes manual or remote interrogation system for storing location and other traffic related behavior and then transmit it by radio broadcast or mobile telephone system to the terminals of road users. However, this information is presented to the users in audio, visual or graphic means, and no attempt is made to provide alternative routes or navigation instructions based on this information.
The present invention contains the vehicle guidance system consisting of a plurality of vehicles equipped with MGUs, the CTU, and a communication system provided by the telecommunication service provider. By utilizing GSM/GPS technology, or GSM technology, or other wireless technology, the CTU tracks the positions of MGUs and updates in real time the database of travel times for all roads. In response to a request from a driver for a route update from his present position to a desired destination, it calculates the desired fastest route by utilizing both the regular travel times along segments of roads and predicted current travel times found by using information collected from tracking routines. Thereafter, the route is communicated to the driver. In addition to GSM it is contemplated that CDMA and other mobile telecommunications formats will be used.
The present invention, provides a real time vehicle guidance system is capable of providing optimal route from the present position of a vehicle to a desired target destination when traffic jams may be present. This reduces the burden upon the driver when the vehicle is traveling at high speeds on unfamiliar roads. Thereafter the optimal route found is communicated to the driver and displayed on the vehicle""s computer screen featuring the digital map of the relevant region and/or via audio instructions.
The travel time between two road intersections A and B is the sum of travel times for all sections of roads connecting A and B on the shortest route either by the minimal time criterion, or by some other criterion. Then in order to be able to compute a travel time between two positions on a map, we must be able to determine travel times for all sections of roads connecting those positions, or road intersections close to them. In the standard solution (an autonomous or stand-alone on-vehicle application), a route is computed by a mathematical optimization algorithm while travel times are computed as distances divided by maximal allowed speeds. While being simple, such solutions have an obvious shortcoming in that they do not take into account the real conditions on the roads and therefore can serve only as a guidance suggestion.
According to one embodiment of the present invention, a true real time system is provided which collect, store and make use of the following kinds of data:
1. Temporary changes in road conditions known in advance like closed roads under construction, traffic reroutes, etc.;
2. Regular predictable changes like everyday slowdowns in rush hours;
3. Sudden unpredictable changes such traffic accidents, traffic congestion due to sudden and drastic changes in traffic arrangements because of visiting dignitaries, etc.
The system in the present invention is built around an idea of collecting and processing information that describes all those changing conditions.
The guidance system according to the present invention consists of CTU and a fleet of MGUs, i.e., traveling vehicles with mobile phones connected to the communication system. Each traveling vehicle may function both as a probe vehicle and as a client vehicle. When a phone handset unit is located in the mounting receptacle, the vehicle functions as a probe vehicle for data collection. This data collection is performed by permanent monitoring of vehicle positions by means of GSM/GPS or other wireless technology while vehicles are in motion and by concurrent measuring of their current travel times along a broad range of roads.
One goal of the invention is to provide a real time travel guidance system capable of handling a driver""s request for a fastest route to any destination. At any point of the journey the driver can enter a request for alternative route and will receive an updated route reflecting the real time traffic situation directly on his display panel. The information will also be updated by visual and audio instructions, and driver""s vehicle position will be displayed on the display unit.
Another goal is to provide the driver with a tool for strategic trip planning. By entering alternate times for future trips and comparing their travel time estimates for the same destination, the driver receives an option to select a trip proposal ideally suited for his needs.